<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    .active {
      color: red;
    }
  </style>
</head>

<body>
  <div id="app">
    <ul>
      <li v-for="(item, index) in movies" 
      :class="{active: currentIndex == index}" 
      @click="liClick(index)">
        {{item}}
      </li>
    </ul>
  </div>

  <script src="../js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        movies: ['HW', 'HZW', 'ZLBHD', 'HEXD'],
        currentIndex: -1
      },
      methods: {
        liClick(index) {
          this.currentIndex = index;
        }
      }
    })
  </script>
</body>

</html>